Electric valve circuit



Feb. 6, v1940. w, w MOE Y 2,189,569

ELECTRIC VALVE CIRCUIT original Filed July '30, 193s Vig. f il VOLTAGEFROM PHASE CONTROL DN NEGATIVE SIDE OF CAPACITANCI 45.

j PQI.

cATHou: l l onor m nzsnsunc: 43( POTENTIAL.. oF DEVICE 5 3s, curo"von-,Bus VOLT/sz A Aa: as um: nunon 35. ACIOSS CAMCTNCI 2 AND RSNSTAIGI44. o' /6 I A:/5 nn: nevlcc I 381s couwcr 20 /7 22 2/ VOLTAGE oucnncmuc: sa.

,f1 f l f 5/ f :mm f f zweeg-5 V" 55 r/ 0 if' D 59 FQA. 56 57 mem, 49TANSFMHll 59 Invent of:

\ 4 William W. Ploe, v

Atbofney.

Patented Feb. 6, 1940 UNITED f STATES ELECTRIC VALVE CIRCUIT William W.Moe, Bridgeport, Conn., assignor to General Electric Company, acorporation of New York Original application July 30, 1938, Serial No.

Divided and this application April 29, 1939, Serial No; 270,889

5 Claims. l (Cl. 172-238) My invention relates to electric valvecircuits and more particularly to electric valve circuits forteffectinga single energization of a load circu1 This application is a division ofmy co-pending patent application, Serial Number 222,255, filed July 30,1938, and assigned to the assignee of the present application.

Electric valve circuits'have been applied to arv l. rangements foreffecting energization of' a load circuit from an alternating currentsupply cir-v cuit during a predetermined interval of time.

The characteristics of electric valve apparatus make possible their usein circuits of this nature.

my invention described hereinafter, I provide a' new and improvedcontrol circuit whereby a predetermined amount of energy may betransmitted to a load circuit from an alternating current cir- Cuit.

It is an object of my invention to provide a new and improved electricvalve circuit.

It is another object of my invention to provide a new and improvedcontrol system for electric v u valve translating apparatus.

It is a further object of my invention to provide a new and improvedelectric valve control system for electric valve translating apparatus.

It is a still further object of my invention to provide a new andimproved phase shifting circuit for controlling electric valves.

Briefly described, in the illustrated embodiment .of my invention, Iprovide a new and improved phase shifting circuit for producing analterhating voltage of variable vphase displacement with respect tothevoltage of an associated alternating current supply circuit. The phaseshifting circuit is of the static type employing a plurality ofimpedance elements and is arranged 5o to provide a control voltageadjustable inphase throughout the leading and lagging quadrants.

Adjustable elements of the phase shifting circuit are yarrangedto permitcontinuous control of the voltage throughout the leading and lagging uquadrants without effecting an appreciable or objectionable variation inthe magnitude of the voltage.

For a better understanding of my invention, reference may be had to thefollowing description taken in connection with the accompanying draw- 5ing, and its scope will be pointed out in the appended claims. Fig. 1 ofthe accompanying drawing diagrammatically illustrates an embodiment ofmy invention as applied to a welding system, and Figs. 2, 3 and 4represent certain operating 10 characteristics thereof. Fig. 5represents certain operating characteristics of the phase shiftingcircuit shown in Fig. 1. Referring now to Fig. 1 of the accompanyingdrawing, my invention is diagrammatically illus- 1g trated as applied toa resistance welding circuit. An electric valve means I is interposedbetween an alternating current supply circuit 2 and a load circuit, suchas agwelding circuit 3. A transformer 4 is connected between thecircuits, and m the electric valve means l may be connected in seriesrelation with a primary winding 5 of the transformer l. The electricvalve means I is preferably of the type employing an ionizable medium,such as a. gas or a vapor, and comprises u an anode 6, a cathode of theself-reconstructing type, such as a mercury pool cathode 1, and anassociated control member 8 of the immersionignitor type having anextremity thereof extending below the surface of the mercury poolcathode .o 1. The immersion-ignitor control member 8 is preferablyconstructed of a material having a relatively high specic electricalresistivity relative to that of the associated cathode 1. For example,the immersion-ignitor control member 8 may be u constructed of amaterial such as boron-carbide or silicon-carbide. An arc discharge isinitiated between the anode 6 and the lcathode 1 when a sufficientlylarge current is transmitted through the immersion-ignitor controlmember 8.

A capacitance 9' is connected to be charged o from a suitable source oi'direct current Il through a charging circuit comprising a resistance Il.A suitable circuit controlling means. such as a switching means orswitch I2, is ar- 45 ranged to selectively connect the condenser 9 tothe charging circuit or to the immersion-ignitor control member 8. Aninductance I3 may be connected in series relation with the controlmember 8 to control the rate of discharge of the w capacitance 9. l

The source of direct current In may be provided by any suitablearrangement and I havechosen to represent it as being supplied by acircuit `Il comprising a transformer I5 having a primary u half cycle ofvoltage, depending upon the time,

during the cycle at which the immersion-ignitor control member 3 isenergized. Of course, it is to be understood that the current whichflows through the electric valve means I is maintained for a period oftime after the line voltage passes through zero, by virtue of theinductance of the associated circuit. The duration of such period orextension in the time of conduction depends upon the power factor of theload circuit.

It is well understood by those skilled in the art that the averagecurrent transmitted by the electric valve means I and hence the amountof energy transmitted to the welding circuit 3 depends upon the timeduring the applied positive half cycle of anode-cathode voltage at whichthe electric valve is rendered conductive. 'I'he energy transmitted tothe welding circuit 3 is increased as the time of'initiation of thedischarge is advanced towards the beginning of the positive half cycleand is, of course, decreased as the time of initiation of the dischargeis retarded.

'I'he manner in which the circuit 32 produces a periodic voltage ofpeaked wave form, which is impressed upon the control member 33 of theelectronic discharge device 21, may be explained by considering theoperating characteristics shown in Figs. 2-4. The capacitance 33 ischarged from the direct current circuit I3 and is discharged atapredetermined time by the electronic discharge device 35. Curve A ofFig. 2 represents the alternating voltage impressed on grid 33 ofdischarge device 35 by the phase shifting circuit 43. Since in thisunitthe discharge device 35 is of the high vacuum type, the grid.

voltageis effective to interrupt as well as-initiate the currenttransmitted by the discharge device. Resistance I4 and capacitance 45and resistor 43 are proportioned to develop a negative biasing potentialof a magnitude such that the electronic discharge device 35 conductscurrent during only a relatively small portion of a cycle as, forexample, a sixty electrical degree interval occurring at about the peakof the voltage wave. Curves B of Fig. 3 represent the currenttransmitted to the primary winding 43 of transformer 33, and curves C ofFig. 4 represent the periodic voltage of peaked wave form induced in thesecondary winding 4I of transformer 33. It will be observed that thepeak of the voltage of peaked wave form, as represented by curves C, isabout thirty electrical degrees ahead of the peak of the output voltagerof the phase shifting circuit 43. To afford complete control of theenergy transmitted to the welding circuit 3, or, in other words, toafford complete control of the heat transmitted to the weld, the phaseshifting network 45 .should be able to supply a voltage the phase ofwhich can be varied in a continuous manner from sixty electrical degreesleading the power voltage of circuit 2 to one hundred twenty electricaldegrees lagging that voltage. Furthermore, for

proper operation of the electronic discharge device 35, the outputvoltage of the phase shifting circuit 46 should also supply a reasonablycony are drawn in their approximate voltage vectorA positions in orderto facilitate explanation of the-operation of the circuit. Vector ODrepresents the voltage appearing between intermediate connection 22 andterminal 2l of winding Il of transformer I5 and, of course, representsthe anode-cathode voltage ofthe electric valve means I. For thetransmission of maximum current to the welding circuit 3, or, in otherwords, for the transmission of maximum welding heat to the work, it isrequired that a voltage leading the voltage of circuit 2 by sixtyelectrical degrees be impressed on the grid 33 of theelectronicdischarge device 35. This voltage is obtained by adjusting the positionof the contact 33 along the resistance 53, as indicated by the dottedlines of Fig. 5. As the contact 33 is moved upward, the voltageimpressed on the grid 33 is advanced in phase with respect to thevoltage of circuit 2, and when it reaches the uppermost position -theangle of advance is maximum.. Conversely, as the adjustable contact 33is moved downward the output voltage of the phase shifting circuit andhence the voltage impressed on grid 33 are retarded with respect to thevoltage of circuit 2. Of course, there is a position for the contact 33at which the potential impressed on the grid 33 is in phase with thevoltage of circuit 2. I have found that the magnitude of lthe voltageimpressed on the grid 33 is constant within a range of approximatelyplus or minus 15% over its operating range. Continuous phase adjustmentof the voltage impressed on grid 33 may be obtained by positioning theadjustable contact 33. The variation in the output voltage of the phaseshifting circuit 43 has a negligible eifect on the operation of theelectronic discharge device 35 and hence has a negligible effect on thepeaked voltage produced by the circuit 32.

. After an impulse of current is transmitted to thev welding circuit 3by moving the switch I2- to the right-hand position, the circuit may bereset by moving the switch I2 to the left-hand position wherecapacitance 9` is recharged through the circuit comprising resistanceIl. The system is then in condition for another welding operation.

An important feature of this type of control is the uniformity of thewelding current which is transmitted to the circuit 3. By virtue of thefact that the welding operation is initiated at a predetermined timeduring each cycle of voltage of circuit 2, the variation in the weldingcurrent is reduced to a minimum since the starting transients may beentirely eliminated, or substantially reduced, by controlling the timeof initiation of the current relative to the power` factor angle of theload circuit. Another irnportant feature is the uniformity of control ofthe magnitude of the periodic voltage of peaked wave form produced bythe circuit 32 and which is substantially independent of variations inthe magnitude of the variable phase output voltage of the phase shiftingcircuit 43.

While I have shown and described my invention as applied to a particularsystem of connections and as embodying various devices diagrammaticallyshown, it will be obvious to those skilled inthe art that changes andmodifications may be made without departing from my invention, and I,therefore, aim in the appended claims to cover all such changes andmodications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In combination, a source of alternating current, a vwinding energizedfrom said source and including terminal connections and a connectionelectrically intermediate the terminal connections, a circuit connectedacross the terminal connections and including a pair of seriallyconnected capacitances and a resistance, said resistance being connectedbetween said capacitances and being provided with an intermediateconnection connected to the intermediate connection of said winding, avoltage divider including a resistance connected across thefirst-mentioned resistance, a capacitance connected between theintermediate connection of the inst-mentioned resistance and anintermediate connection of the second-mentioned resistance, and anoutput circuit connected between Athe intermediate connection of saidwinding and said voltage divider.

2. In combination, a source of alternating current, a winding energizedfrom said source and including terminal connections and a connectionelectrically intermediate the terminal connections, a circuit connectedacross the terminal connections and including a pair of seriallyconnected capacitances and a resistance, said resistance being connectedbetween said capacitances and being provided with' an intermediateconnection connected to the intermediate connection of said winding, Aavoltage divider including a resistance connected across the firstmentioned resistance, a capacitance connected between'the intermediateconnection ofthe Amst-mentioned resistance and an intermediateconnection of the second-mentioned resistance; an impedance elementconnected between one terminal of said winding and the intermediateconnection of said second-mentioned resistance. and an output circuitconnected between the intermediate, connection of said winding and saidvoltage divider.

3. In combination, asource of alternating current, a winding energizedfrom said source and vhaving terminal connections and a. connectionelectrically intermediate the terminal connections, a circuit connectedacross the terminal connections and including a pair cf serially con' yasecond resistance connected across the rstmentioned resistance and beingprovided with an intermediate connection, a capacitance connectedbetween the intermediate connections of first-mentioned resistance andthe second resistance, and an output circuit having one terminalconnected to the intermediate connection of said winding and anadjustable terminal connected to the second resistance. o

4. In combination, a source of alternating current, a winding venergizedfrom said source and having terminal connections and a connectionelectrically intermediate the terminal connections, a circuit connectedacross the terminal v connections and comprising, a pair of seriallyconnected capacitances anda resistance, said Vresistance beingconnectedbetween the capacitances and having an intermediate connectionconnected to the intermediate connection of said winding, a secondresistance connected across the first-mentioned resistance, acapacitance connected between the intermediate connection of themst-mentioned resistance and in intermediate connection of the secondresistance, an output'circuit having one terminal connected to theintermediate connection of said winding, and means for controlling thephase of the voltageof the output circuit relative to the voltage ofsaid source. l v

5.l In combination, a source of alternating current, la windingenergized from said source and having terminal connections andaconnection electrically intermediate the terminal connec-v tions, acircuit connected -ac'ross the terminal connections and comprisin v.apair oi' serially connected capacitances f an connected to theintermediate connection of said Winding, a second resistance connectedacross the first-mentioned resistance, a" capacitance connected betweenthe intermediate connection of the first-mentioned resistance and aninter-- mediate connection ofthe second resistance. an output circuithaving one terminal connected to the intermediate connection of saidwinding, and means for continuously controlling the phase, of the outputcircuit from a predetermined leading angle relative to the voltage ofsaid source to a predetermined lagging angle and comprising anadjustable contact memberfassociated with the second resistance.

WILLIAM W. MOE.

n a resistance, said vresistance being connected between thecapacitances and having an intermediate connection

